1. Field of the Invention
This invention relates in general to flush valves for water closets, urinals and other plumbing equipment. More particularly, the invention relates to an improved diaphragm for use in flush valves.
2. Description of the Prior Art
Flush valves in water closets, urinals and other plumbing devices which utilize a flexible diaphragm to establish and to seal off the connection between the inlet and outlet are well-known in the art. Typically, the diaphragm is made of an elastomeric material, such as rubber, and includes a bypass which provides fluid communication between the inlet side of the flush valve and an upper chamber of the flush valve. A typical prior art diaphragm is shown in FIG. 1 of U.S. Pat. No. 5,232,194 to Saadi et al. (hereinafter "the Saadi patent"), and is incorporated herein by reference.
The Saadi patent also discloses a unitary diaphragm assembly that includes a diaphragm having a cylindrically-shaped bypass orifice formed therein and is illustrated in FIGS. 2 and 3 of the present patent application.
The performance of prior art diaphragms varies depending on the pressure drop between the opposite sides of the diaphragm due to the bypass orifice. Specifically, a higher pressure difference across the diaphragm, such as will occur on a bottom floor of a multistory building, causes more water to pass through the flush valve for a fixed period of time when the flush valve is activated. Likewise, in a situation where there is a low pressure difference across the diaphragm, less water will flow through the flush valve when it is activated. Hence, the amount of water flowing through the flush valve is a function of the supply of water pressure to the flush valve.
Therefore, it is an object of the present invention to provide an improved diaphragm orifice to compensate for pressure differentials across the diaphragm and improve valve performance.